Coupled fluid injection with volume determined by pressure
AssigneeIncoe Corporation
InventorJames W. Hendry
Life of this patent
Estimating the term…
Abstract
A gas assisted molding apparatus having gas introduced into the plastic charge as the charge is flowing into the mold cavity. The gas and plastic are simultaneously injected into the mold cavity and the gas can be introduced at the nozzle end or barrel of the injection molding machine. Optionally, the gas may be injected into a hot runner manifold or into the cavity itself simultaneously with the plastic. The apparatus includes a conventional gas injection mold, a source of inert gas, such as nitrogen, and an injection assembly. A common power source is used for both the injection of the plastic and the gas to assure simultaneous inflow of both the gas and the molten plastic at the same pressure.
Claims34
A method for creating an injection molded plastic article with a hollow chamber therein and utilizing an injection molding machine, a mold with a cavity, and a gas injection mechanism, the injection molding machine having a barrel with an injection end and a rotatable and longitudinally moveable screw positioned in the barrel, said method comprising the steps of:
- determining the volume of said mold cavity;
- determining the pressure necessary to fill said mold cavity with plastic material;
- determining the amounts by volume of plastic material and gas desired in said mold cavity, wherein the volume of gas is determined and fixed by said pressure;
- injecting said determined volume of plastic material into said mold cavity;
- and
- injecting said determined and fixed volume of gas into said plastic material in said mold cavity, while maintaining the pressure of said gas substantially constantly with the plastic pressure, said injection of said gas being delayed until sufficient plastic material has been injected into said mold cavity thereby preventing passage of said gas completely through said plastic material and causing blow-out.
A method for creating an injection molded plastic article with a hollow chamber therein and utilizing an injection molding machine, a mold with a cavity, and a gas injection mechanism, the injection molding machine having a barrel with an injection end and a rotatable and longitudinally moveable screw positioned in the barrel, said method comprising the steps of:
- determining the volume of said mold cavity;
- determining the pressure necessary to fill said mold cavity with plastic material;
- determining the amounts by volume of plastic material and gas desired in said mold cavity, wherein the volume of gas is determined by said pressure;
- starting to inject said determined volume of plastic material into said mold cavity to form a plastic material melt stream;
- and
- injecting said determined volume of gas into said plastic material melt stream in said mold cavity while maintaining the pressure of plastic injection substantially constant with said gas pressure.
A method for creating an injection molded plastic article with a hollow chamber therein and utilizing an injection molding machine, a mold with a cavity, and a gas injection mechanism, the injection molding machine having a barrel with an injection end and a rotatable and longitudinally moveable screw positioned in the barrel, said method comprising the steps of:
- determining the volume of said mold cavity;
- determining the pressure necessary to fill said mold cavity with plastic material;
- determining the amounts by volume of plastic material and gas desired in said mold cavity, wherein the volume of gas is determined by said pressure;
- injecting said determined volume of plastic material into said mold cavity;
- injecting said determined volume of gas into said plastic material in said mold cavity;
- and
- stopping and then restarting the injection of gas into the plastic material.
A method for creating an injection molded plastic article with a hollow chamber therein and utilizing an injection molding machine, a mold with a cavity, and a gas injection mechanism, the injection molding machine having a barrel with an injection end and a rotatable and longitudinally moveable screw positioned in the barrel, said method comprising the steps of:
- determining the volume of said mold cavity;
- determining the pressure necessary to fill said mold cavity with plastic material;
- determining the amounts by volume of plastic material and gas desired in said mold cavity, wherein the volume of gas is determined by said pressure;
- injecting said determined volume of plastic material into said mold cavity;
- injecting said determined volume of gas into said plastic material in said mold cavity;
- and
- continuing said injection of gas until said screw in said extruder barrel has bottomed out.
A method for creating an injection molded plastic article with a hollow chamber therein and utilizing an injection molding machine, a mold with a cavity, and a gas injection mechanism, the injection molding machine having a barrel with an injection end and a rotatable and longitudinally moveable screw positioned in the barrel, said method comprising the steps of:
- determining the volume of said mold cavity;
- determining the pressure necessary to fill said mold cavity with plastic material;
- determining the amounts by volume of plastic material and gas desired in said mold cavity, wherein the volume of gas is determined by said pressure;
- injecting said determined volume of plastic material into said mold cavity;
- and
- injecting said determined volume of gas into said plastic material in said mold cavity;
- wherein said quantity of gas is injected from a compression chamber with a moveable piston and said quantity of gas is fully injected into said plastic material when said piston has traveled its full stroke in said compression chamber.
A method for creating an injection molded plastic article with a hollow chamber therein and utilizing an injection molding machine, a mold with a cavity, and a gas injection mechanism, the injection molding machine having a barrel with an injection end and a rotatable and longitudinally moveable screw positioned in the barrel, said method comprising the steps of:
- determining the volume of said mold cavity;
- determining the pressure necessary to fill said mold cavity with plastic material;
- determining the amounts by volume of plastic material and gas desired in said mold cavity, wherein the volume of gas is determined by said pressure;
- injecting said determined volume of plastic material into said mold cavity;
- and
- injecting said determined volume of gas into said plastic material in said mold cavity;
- wherein the plastic material is injected into said mold cavity and said gas is injected into said plastic material at the same rates of speed.
A method for creating an injection molded plastic article with a hollow chamber therein and utilizing an injection molding machine, a mold with a cavity, and a gas injection mechanism, the injection molding machine having a barrel with an injection end and a rotatable and longitudinally moveable screw positioned in the:
- barrel, said method comprising the steps of:
- determining the volume of said mold cavity;
- determining the pressure necessary to fill said mold cavity with plastic material;
- determining the amounts by volume of plastic material and gas desired in said mold cavity, wherein the volume of gas is determined by said pressure;
- injecting said determined volume of plastic material into said mold cavity;
- and
- injecting said determined volume of gas into said plastic material in said mold cavity;
- wherein the plastic material is injected into said mold cavity and said gas is injected into said plastic material at different rates of speed.
A method for creating an injection molded plastic article with a hollow chamber therein and utilizing an injection molding machine, a mold with a cavity, and a gas injection mechanism, and at least one power source for injecting, the plastic and gas, the injection molding machine having a barrel with an injection end and a rotatable and longitudinally moveable screw positioned in the barrel, said method comprising the steps of:
- determining the volume of said mold cavity;
- determining the pressure necessary to fill said mold cavity with plastic material;
- determining the amounts by volume of plastic material and gas desired in said mold cavity, wherein the volume of gas is determined by said pressure;
- injecting said determined volume of plastic material into said mold cavity;
- and
- injecting said determined volume of gas into said plastic material in said mold cavity;
- wherein said gas and said plastic material are injected into said mold cavity using the same power source.
Dependencies are inferred from the claim text.